1. Field of the Invention
The present invention relates to a frequency characteristic measuring apparatus for measuring a frequency characteristic or the like of an input signal in a spectrum analyzer having a tracking generator function.
2. Description of the Related Art
A spectrum analyzer is known which incorporates a tracking generator, and which is capable of separately setting a frequency sweep range through which an output signal from the tracking generator is swept and a frequency sweep range through which a frequency characteristic is measured (see, for example, Japanese Patent Laid-Open No. 7-260825). With this spectrum analyzer, a frequency characteristic of a device under test, e.g., a frequency converter having an output frequency different from an input frequency can be measured.
In many cases, an ordinary spectrum analyzer having a tracking generator is used for measurement of a frequency characteristic of a device under test having an output frequency and an input frequency equal to each other (ordinary measurement). With the spectrum analyzer disclosed in Japanese Patent Laid-Open No. 7-260825, therefore, there is a problem that the tracking generator or peripheral circuits associated with the tracking generator are made complicated for selective execution of the ordinary measurement and a measurement suitable for a frequency converter or the like.
Also, the conventional spectrum analyzer is capable of measuring a frequency characteristic of an output signal from a device under test but incapable of simultaneously measuring a frequency characteristic of a signal input to the device under test and incapable of comparing the characteristics of the input signal and the output signal.